ᐅ Roof Covering and Choosing a Solar Installer – Making the Decision?

Hello everyone,

I am about to decide whether to hire a solar installer. I am building a turnkey single-family house with a general contractor in the 84xxx area, featuring a gable roof with a 25° pitch, oriented north/south. There are no skylights, chimney, or other obstructions on the roof, so conditions are optimal.

I am having some difficulty even requesting quotes and now have at least two offers. I would appreciate help evaluating and choosing between them (both the company and whether to include the north side). I have not asked for a battery system but might consider adding one later if it becomes more affordable.

So, first I am facing the question: include north side or not? I can fit about 25 modules on each side, resulting in roughly 10 kWp. PVGIS estimates around 10,000 kWh for south and about 7,000 kWh for north.

Offer 1 comes from a solar installer with many years of experience, who not only works on single-family houses but also builds large-scale systems in the megawatt range. My general contractor, who is building the house turnkey, also has long-standing experience with this installer and recommends them.

Offer 1 details:
- 20.5 kWp
- 50 x Q-Cells Q-Peak ML G10 410 heat pump compatible modules
- 50 x SolarEdge Power Optimizers, S440 Worldwide (v1)
- SolarEdge StorEdge three-phase inverters: SE10K-RWS-EU-APAC/AUS (v1) and SE7K-RWS-EU-APAC (v1)
- SolarEdge Smart Meter for self-consumption monitoring
- All other materials, installation, and commissioning services included
- Cost: €31,980 net, which equals approximately €1,560 net per kWp — reasonable for today, not really cheap but not very expensive either

Now to Offer 2. This offer is from a very small and new electrical company I found through a neighbor's recommendation. The company does not even have a finished website yet because it is so new, but they have already done electrical work in the development area (not sure about PV though). Two different neighbors have told me this company is good.

Offer 2 details:
- 20.9 kWp
- 51 x JinkoSolar Tiger NE HC N-Type black solar modules JKM410N-54HL4-B
- 2 x SMA inverters STP10.0-3SE-40
- 1 x SMA Sunny Home Manager HM-20
- Other materials are not specified here, but all installation, planning, and commissioning services are included
- Cost: €25,570 net, equaling approximately €1,223 net per kWp

My questions now:
- What do you generally think about the materials used?
- Are the SolarEdge power optimizers in Offer 1 really necessary? I expect practically no shading from trees, chimney, or anything else given the location
- Company 2 is probably a bit risky, but the price is really attractive. Is it worth taking the risk here?
- Does installing modules on the north side make sense at all in the case of Offer 1? If I calculate north and south separately, south obviously makes sense in both cases. North seems worthwhile (based on my calculation) only with Offer 2... with Offer 1 I would be running at a loss.

I would be very grateful for a brief assessment!

Best regards

Elias_dee schrieb:

- What do you think generally about the materials used?

Both do what they are supposed to do.

Elias_dee schrieb:

- Are the SolarEdge power optimizers really necessary in offer 1?

No, you can skip them.

Elias_dee schrieb:

- Company 2 is probably a bit risky, but the price is really very attractive. Is it worth taking the risk here?

What risk? Every photovoltaic system I have installed so far was only paid after material delivery, installation, and final commissioning. Not a single euro in advance.

Elias_dee schrieb:

- Is the north-facing orientation worth it in the case of offer 1? When I calculate north and south, south is obviously more profitable in both cases. North pays off (according to my calculation) only with offer 2... with offer 1 I would make a loss.

Financed or own capital? What about self-consumption (electric car)?
I would go for both sides. Just south probably costs around €15,000 net, so north would be an additional €10,000.

SaniererNRW123 schrieb:

Both do what they are supposed to.

No, you can skip that.

What risk? Every photovoltaic system I have installed so far was only paid after material delivery, installation, and final commissioning. Not a single euro in advance.

Financing or equity? What is the self-consumption (electric car)?
I would take both sides. Only south probably costs about €15,000 net, so north in addition only about €10,000.

Thank you very much for your helpful reply! You are right about the risk. Self-consumption is about 10,000 kWh (including air-water heat pump), no electric car yet (but that might come eventually).

Regarding SolarEdge: the solar installer probably included it because it requires little effort for them and brings good profit, right? According to Google, they cost between €60 and €100. So it should make up something in the range of €3,000 to €5,000 in the offer.

I would tend to go with offer 2 (but definitely a "full roof") since the SE is completely unnecessary. In addition, the SMA components are supposed to be quite good.
The only question I have about offer No 2 is why are there 2 inverters? It might be that currently only what is available can be used.
PVGIS is conservative; usually, the system produces a bit more from the roof than indicated there.
What do both say about delivery times?

Elias_dee schrieb:

Self-consumption is about 10,000 kWh (including air-to-water heat pump), no electric car yet (but it might come eventually).

I doubt that. How do you arrive at that level of self-consumption? I have a 10 kW solar photovoltaic system including an electric car (hybrid and working from home, so sometimes charging 2-3 times daily with 10 kWh each) as well as an air-to-water heat pump, and I would be happy to have such a self-consumption rate.

SaniererNRW123 schrieb:

I doubt that. How do you come to that self-consumption amount? I have a 10 kW photovoltaic system including an electric car (hybrid and working from home, so charging 2-3 times a day with about 10 kWh each time), as well as an air-to-water heat pump, and I would be happy with such a self-consumption rate.

Oh, sorry. I actually meant the total annual consumption of our household. So 10,000 kWh overall. I estimate the self-consumption to be around 2,000 kWh.